Because of its trajectory, which indicated that it came from another solar system, and its odd spearhead shape, scientists speculated that it could be an alien spacecraft cleverly disguised as a rock.

Breakthrough Listen, a $100 million venture searching for intelligent life in the universe, is trying to determine if the 400-meter-long asteroid, dubbed Oumuamua, could have artificial origins. The initiative is backed by British physicist Stephen Hawking, Russian digital tech mogul Yuri Milner and Facebook chief Mark Zuckerberg.

According to a statement from Breakthrough, the project's team listened across four radio bands that spanned billions of individual channels Wednesday, using an instrument on the 330-foot Green Bank radio telescope dish in West Virginia. The initial block of data (the first of a planned four blocks) detected no unusual signals.

Artist’s concept of interstellar asteroid 1I/2017 U1 (a.k.a. Oumuamua) as it passed through the solar system after its discovery in October 2017. The aspect ratio of up to 10:1 is unlike that of any object seen in our own solar system. (European Southern Observatory/M. Kornmesser))

Artist’s concept of interstellar asteroid 1I/2017 U1 (a.k.a....

Because of the size of the observation blocks, it will take Breakthrough Listen "some time to complete" the investigation, project representatives said.

Scientists at the SETI Institute in Mountain View have already searched for signals coming from the asteroid using the Allen Telescope Array, a few hundred miles north of San Francisco.